Self‐reported poor sleep accelerates hippocampal volume loss in cognitively normal healthy elderly

Abstract

AbstractBackgroundPoor sleep quality is a known risk factor for the development of Alzheimer’s disease (AD). However, minimal data is available on the rate of brain tissue volume loss related to self‐reported poor sleep. Our previous cross‐sectional study in cognitively normal elderly adults age 60 and over, demonstrated that poor sleepers exhibited significantly smaller volumes, approximately 7%, in the bilateral hippocampi, superior parietal lobules and left amygdala and smaller cortical thicknesses, over 3%, in the right superior frontal, medial orbitofrontal cortices and frontal pole, compared to normal sleepers (Alperin et al, 2019). Current study is a follow‐up longitudinal investigation comparing rates of tissue loss in these brain regions of interest (ROIs) between elderly good and poor sleepers with normal cognition.MethodForty‐eight cognitively normal elderly individuals age 60 to 92 years were classified into two groups: 23 normal sleepers with self‐reported Pittsburgh Sleep Quality Index (PSQI) < 5 and 25 poor sleepers with PSQI ≥ 5. The two groups were equivalent in terms of age, gender, years of education and white matter hyperintensity (WMH) load. The volumes and thickness of the ROIs were measured at baseline and at follow‐up scans to assess rates of tissue loss using FreeSurfer software. Rates of tissue loss over 2 years were compared between two groups.ResultNo significant association was found between sleep quality, WMH load and rates of thickness loss. Compared to normal sleepers, poor sleepers exhibited 2.8 times higher rates of volume loss in the hippocampus, and 3.3 times higher rate in the posterior cingulate. Global PSQI at baseline was significantly and negatively associated with rates of volume loss in the right hippocampus (rs=‐0.33) and right posterior cingulate cortex (rs=‐0.47). Scores in verbal memory was negatively associated with rates of volume loss in the right hippocampus (r≥0.388).ConclusionPoor sleep quality is associated with significantly accelerated volume loss in the hippocampus and the posterior cingulate cortex in cognitively normal elderly individuals. Intervention for improving sleep quality should be highly considered in cognitively normal elderly adults to delay onset of cognitive impairment and onset of AD.